1. Field of the Invention
The present invention relates to a closed type motor-operated compressor, and mainly relates to the closed type motor-operated compressor for use in air conditioning and refrigerating, in particular, being suitable for achieving improvement on performances of refrigerating cycle thereof.
2. Description of Prior Art
The prior art will be explained by referring to Japanese Patent Laying-open No. Hei 5-99182 (1993) and Japanese Patent Laying-open No. 2000-073977 (2000), in particular, the structure of the closed type motor-operated compressor according to the conventional art, shown in FIG. 6 attached therewith, while constituent members or elements relating thereto in FIGS. 7 and 8.
FIG. 6 is the cross-section view for showing an example of the conventional closed type motor-operated compressor 21. Namely, in a central portion of a cylindrical case 23 as a main body of a hermetically sealed container 22, being welded with a cover chamber 24 at the upper portion and with a bottom chamber at the lower portion thereof, a stator 26a of a motor 26 is disposed on an outer side while a rotor 26b on an inner side, and a compression mechanism portion 27, which is directly connected to the rotor 26b by means of a crankshaft 28, is disposed in an upper portion thereof. Also, a sub- or auxiliary bearing 33 connected with the lower end side of the crank shaft 28 and a support portion 34 (with bores 34a) for supporting the auxiliary bearing 33, which has a hole or bore for collecting circulating refrigerating machine oil therethrough, are disposed in a lower portion of the case 23. Also, within the lowest portion of the sealed container 22 on a side of the bottom chamber 25 is enclosed the refrigerating machine oil 35.
The compressor mechanism portion 27 is formed with a stationary scroll 32, which is screwed to a frame 29 by means of a bolt(s). The frame 29 comprises a bearing 29b for insertion of the crankshaft 28, and a hole 29c for receiving discharge pipe 23a. Between the stationary scroll 32 and the frame 29 is provided a rotational scroll 31. A swirl 31d of the rotational scroll 31 and a swirl 32b of the stationary scroll 32 are assembled together in such a manner that the rotational scroll 31 is able to wobble freely. The compressor mechanism portion 27 receives the rotational scroll 31 within a step-wise portion 29a of the frame 29, while keeping it freely slidable thereon. In the compressor mechanism portion 27, for the purpose of preventing the rotational scroll 31 from rotating on its own axis, there is provided an Oldham ring 30 having keys 30a, being formed on upper and lower surfaces of the ring, so that they cross at right angles to one another. Those keys 30a are inserted into key groove (not shown in the figure) of the frame 29 and the key seats 31a of the rotational scroll 31, respectively.
Oil supply to the compressor mechanism portion 27 is provided, for the purpose of lubricating the crankshaft 28 and the frame 29, the bearing portions 29b and 31c of the rotational scroll 31, and sliding surfaces of the key groove of the rotational scroll 31 and the frame 29 and the keys 30a of the Oldham ring 30, respectively, and also improving a property of gas sealing between the swirls 32b and 31d of the stationary scroll 32 and the rotational scroll 31, between a mirror plate 31b of the rotational scroll 31 and the step-wise portion 29a of the frame 29, and between end surfaces 32c of the stationary scroll 32, wherein the refrigerating machine oil 35 in a lower portion of the sealed container 22 is loaded at an intermediate pressure between an discharge pressure and a suction pressure of the compressor, so that it is supplied to each portion through an oil supply bore 28a opened in a central portion of the crankshaft 28.
With such the conventional closed type motor-operated compressor 21 already-known, refrigerant gas (hereinafter, xe2x80x9csuction gasxe2x80x9d), which is enclosed within the refrigerating cycle in advance, is sucked from a suction pipe 24a connecting between an external portion of the sealed container 22 and the stationary scroll 32, due to pumping function of a compressor chamber defined by the swirls 32b and 31d of the stationary scroll 32 and the rotational scroll 31, accompanying the rotation of the motor 26, and after being compressed sequentially, it is discharged within the sealed container 22, in a form of high pressure gas (hereinafter, xe2x80x9cdischarge gasxe2x80x9d), from a discharge hole 32a which is opened in the vicinity of a center of the stationary scroll 32.
In this instance, the refrigerating machine oil, which is supplied onto the sliding surfaces for improving reliability as was mentioned in the above, as well as the same one that is supplied onto sealing surfaces for improving the property of gas sealing, is mixed with the suction gas to be compressed, and it is discharged into the sealed container 22 under a condition of mist together with the discharge gas. This gas flows out from a discharge pipe 23a of the case 23 into the refrigerating cycle (not shown in the figure) in the outside of the sealed container 22, and the refrigerating machine oil of the mist-like condition adheres in the form of an oil film onto an inner surface of a pipe (not shown in the figure) of the refrigerator, thereby preventing heat radiation in a heat exchanger and reducing down an efficiency in heat exchange thereof, therefore it is impossible to achieve good performance on an air conditioner and refrigerating machines.
Then, in the conventional closed type motor-operated compressor 21, for suppressing the flow-out of the oil mist contained within the discharge gas into the refrigerating cycle, a shielding space or room 38 is formed by using a lower side of the frame 29 of the compressor mechanism portion 27, an oil ring 36 between an upper end coil 26c of the motor 26, and an oil cover 37 having a bent portion 37a which covers an outer diameter side and an upper surface of the upper end coil 26c, wherein a tip of the discharge pipe 23a projecting from the case 23 is inserted within the shielding space 38, penetrating through a cutting 36a which is provided in a portion of the above-mentioned oil ring 36, then no discharge gas flows into the discharge pipe 23a directly from a space between the frame 29 and the motor 26.
Namely, explaining the method for preventing the flow-out of oil mist in more details thereof, the shielding space 38 is formed by using both members of the oil ring 36 mentioned above and the oil cover 37, while inserting the tip of the discharge pipe 23a into the said shielding space 38, therefore the discharge gas containing the mist-like refrigerating machine oil therein, being discharged from the compressor mechanism portion 27, as shown by an arrow in the FIG. 6, and passing through a space or gap defined by the inner diameter of the case 23 and an outer periphery cut portion 26f of a core 26e of the motor 26, goes past lower part end coil 26d and up within an air gap between the stator 26a and the rotor 26b from a lower portion of the motor 26, thereby being guided to the discharge pipe 23a. 
As a result of this, comparing to the case of no such the shielding space 38, since the passage of the discharge gas is long and the passage is continuous while being reduced down or expanded in the cross-section area thereof, the mist-like refrigerating machine oil 35 mixed within the discharge gas is separated from, and it is liquefied to drip into the lower portion of the sealed container 22. The refrigerating machine oil flowing into the refrigerating cycle is restricted in flow-out amount thereof at a certain degree, therefore it is possible to relieve formation of oil film within the pipe of the refrigerating cycle, thereby to improve the performance of heat-exchange in the air conditioner or the refrigerating machines.
FIG. 7 is a perspective view for showing an example of a shape of the oil ring 36. FIG. 8 is a perspective view for showing an example of a shape of the oil cover 37.
Both of the members have cylindrical portions being concentric with an axis of the closed type motor-operated compressor, wherein the oil cover 37 is formed with a bent portion 37a of width for covering the upper surface of the upper end coil 26c, while the oil ring 36 has a diameter size within the range of the width of the bent portion 37a of the oil cover 37, and those both members, as shown in the FIG. 6, are elastically engaged with between the frame 29 and the end surface of the core 26e of the motor 26, by using elasticity of the bent portion 37a of the oil cover 37. In this instance, in general, both members are made from a resin film that has a property of electric insulation.
In the closed type motor-operated compressor explained as the conventional art in the above, the passage for the compressed gas is arranged in the structure, so that large one and small one are mixed with in the cross-section area thereof, to decelerate the flow velocity of the gas therein, thereby condensing the oil mist indirectly, so as to bring about dews along the gas passage, to drip it into the lower portion of the compressor.
However, because of an intention of saving electric power increasing more and more in the industry of the air conditioner and the refrigerating machines, it is a proposition to obtain an improvement on the performance of the heat exchanger, and there is a necessity of preventing the oil from further flowing out into the pipe of the refrigerating machine, to improve the performance or capacity of heat radiation of the pipe, therefore there is a demand of separating the oil from the discharge gas more than that in the conventional closed type motor-operated compressor.
According to the present invention, it is an object to provide a closed type motor-operated compressor, wherein the refrigerating machine oil is further prevented from flowing out from the compressor into the refrigerating cycle than that in the conventional art, with less oil in the refrigerating cycle system being less of a deterrent for heat dissipation, thereby increasing the efficiency of heat exchange by the heat exchanger thereof.
For accomplishing the object mentioned above, according to the present invention, there is provided a closed type motor-operated compressor, wherein the oil is separated from the refrigerant gas, which is compressed within the compressor, by using a filter with high efficiency.